The invention pertains to the field of selective animal feeders wherein the dispensing of feed is controlled by an actuator worn by the animal to be fed.
In order to achieve maximum milk production in a dairy herd, it is now known to provide automatic feed dispensing apparatus which selectively provides predetermined animals with supplemental feed. Dairy herds are normally free to roam a feed lot between milkings, and by providing selected animals with supplemental feed while within the feed lot may substantially increase the milk production of a particular cow, but because of age, size, and other factors it is often undesirable that all of the animals of the herd receive such supplemental feeding. Also, due to the expense of the supplemental feed it is important that the dispensing thereof be accurately controlled to minimize waste.
A number of prior art devices have been proposed for controlling the selective feeding of animals and many of these devices include sophisticated circuitry and apparatus as disclosed in U.S. Pat. Nos. 3,465,724, 3,541,995 and 3,557,758. Such devices often include feed dispenser actuating means worn by the animal, such as a tuned circuit capable of modifying a transmitted signal, and while such devices are capable of selectively feeding animals the cost and maintenance thereof have placed such devices beyond the availability of all but the larger milk producing operations.
In my U.S. Pat. No. 3,557,757 I have disclosed a relatively inexpensive selective feeder operated by a magnet worn by the animal to be fed, and this patent further discloses additional means for actuating the feed transfer mechanism. Also, U.S. Pat. No. 3,850,145 discloses a relatively inexpensive supplemental feeder for cows wherein a passive device worn by the animal actuates a switch having a magnet mounted thereon for energizing feed dispensing means. While the two patents mentioned above do provide inexpensive selective animal feeders within the availability of the small and medium size dairy farmer, such magnetically controlled devices will only permit operation of a single type of feeder since actuation of the feed transfer means is controlled by the presence or absence of a non-discriminating magnetic field, and the devices disclosed in both of these patents are incapable of permitting two separate feed dispensers to be utilized having separate actuating means wherein the control circuits are capable of distinguishing the characteristics of a magnetic field to selectively control feed dispensing.